9 June - Odema and adelgids

Cultural work Shade eucalyptus growing under protection to prevent oedema -- corky patches on leaves -- in warm, humid conditions. Improve airflow on protected crops of Buddleja, Digitalis and Phygelius to reduce the risk of black sticky spots on leaves and stems.

Adelgids Control these woolly aphid-like pests using Decis  (non-IPM, EAMU 2014-1011) 

or Hallmark WZT (non-IPM, EAMU 2008-2944) as well as a wetting agent — where product appropriate — for better foliage penetration. Nymphs form pineapple-shaped galls, in which they develop, on Abies, juniper, larch, Picea, pine and Pseudotsuga. Galls are usually larger on young strong shoots.

Ash leaf sucker Prevalent this month, causing leaf-edge curling and purple discolouration. Apply Decis (EAMU 2014-1011) or Hallmark WZT (EAMU 2008-2944) if required.

Wilting Apply an anti-transpirant such as Wiltpruf S600 to newly potted crops to prevent unnecessary moisture loss and wind damage. Check irrigation programmes daily to make sure that they are appropriate to the weather conditions and irrigate during cooler periods of the day to avoid leaf scorch on soft foliage. In addition, reduce controlled-release fertiliser amounts by 10 per cent to avoid root damage this summer.

Escallonia Avoid yellowing and defoliation of lower leaves by applying foliar sprays of Epsom salts (magnesium sulphate) applied at 15g per litre of water
to run-off.

Irrigation Regularly check all crops along bed edges and pathways — do not assume that automatic irrigation systems are producing an even output at the right intervals.

Phoma Infections can cause tip and stem dieback on ceanothus and viburnum. Control with Octave, Serenade ASO (EAMUs required), Switch or Signum (EAMU 2012-2141).

Spider mites These pests are currently extremely active on vulnerable crops. Control using Dynamec, Hallmark WZT  (non-IPM, EAMU 2008-2944), Naturalis-L, Oberon (EAMU 2004-1718) or SB Plant Invigorator. Some of the less harmful products may still cause some temporary damage to sensitive predators such as Phytoseiulus persimilis. Switch to more heat-tolerant species such as Amblyseius andersoni or  A. californicus instead for spider mite control.

Spraying If dilute washings are sprayed back over crops then make sure that the maximum product dose is not exceeded. If washings are applied onto non-crop land then an environmental permit will be required.

John Adlam is managing director, Dove Associates

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